The present invention relates to mounting systems. More particularly, the present invention relates to systems and methods for mounting solar energy capture systems to an outdoor surface.
Solar energy capture systems, such as photovoltaic (PV) arrays, can be used to convert solar energy into electricity. For ease of manufacturing and assembly, these solar energy capture systems typically include framed modular solar panels. While the processes of solar-based electrical generation and conversion have undergone many innovative changes, the techniques for mounting the solar panels have not been as well understood or studied.
In most installations, the solar panels are mounted in a “tilted” configuration in order to capture more solar radiation, i.e., the solar panels are better aligned with the solar angle of incidence. In mounting these tilted solar panels, the cause and effect of loads on the mounting surface must be understood and resolved, and these loads include standing loads and variable loads, also commonly called dead loads and live loads, respectively.
Standing loads are the result of the combined weight of the solar panels and the mounting system. These standing loads are predictable and hence easier to accommodate for during the installation of solar panels and mounting system.
Variable loads on tilted solar panels are mainly caused by environmental conditions, such as wind, rain, snow, hail, etc. Other potential environmental hazards include seismic events, temperature extremes, debris, and mold. In order to be able to reliably predict and accommodate variable loads, these environmental problems have to be understood and resolved, the most common and problematic being wind-induced forces (including hurricanes and tornadoes), namely lift and drag forces generated by the wind conditions. A variety of mounting systems which are commercially available for mounting solar panels attempt to address the wind-induced forces. Most of these mounting systems can be divided into several general categories: non-tilted solar panels, enclosed tilted solar panels, and tilted solar panels with wind deflectors attached to every row.
U.S. Pat. No. 5,746,839 (Dinwoodie) and U.S. Pat. No. 6,570,084 (Dinwoodie), are examples of implementations involving non-tilted solar panels. While non-tilted solar panels do present a lower profile with respect to the wind forces, they are less efficient at converting solar energy to electrical energy when installed at locations with higher latitudes. Another disadvantage of a non-tilted system is the accumulation of dirt, dust, debris and snow on top of the solar panels which can further reduce the conversion efficiency of these solar panels.
Moulder et al., U.S. Patent application 2004/0128923, discloses an example of an enclosed tilted solar panel system. While such a design offers advantages such as improved rigidity, less debris accumulation, and better protection of electrical components, an enclosed solar panel system unnecessarily increases the cost and weight of the system, is likely to increase wind-induced drag forces and also significantly reduces beneficial cooling from natural airflow.
In U.S. Pat. No. 6,063,996 (Takada), U.S. Pat. No. 6,809,251 (Dinwoodie) and U.S. Application 2004/0250491 (Diaz et al.), deflectors are installed on the north-facing back of every panel in order to reduce the wind-induced uplift forces, when installed in the northern hemisphere. Disadvantages of such systems include significantly increased cost and weight of the installed system. In addition, reduced cooling of the solar panels can also significantly reduce the solar conversion efficiency of the system.
In sum, the solar panel mounting systems described above all have significant disadvantages such as increased cost, increased weight, increased drag and propensity for reduced energy conversion efficiency. Hence there is a need for an improved system for mounting solar panels that is superior to these approaches while mitigating these drawbacks.